E-health encompasses a diverse set of informatics tools that have been designed to improve public health and health care. Little information is available on the impacts of e-health programmes, particularly in low- and middle-income countries. We therefore conducted a scoping review of the published and non-published literature to identify data on the effects of e-health on health outcomes and costs. The emphasis was on the identification of unanswered questions for future research, particularly on topics relevant to low- and middle-income countries. Although e-health tools supporting clinical practice have growing penetration globally, there is more evidence of benefits for tools that support clinical decisions and laboratory information systems than for those that support picture archiving and communication systems. Community information systems for disease surveillance have been implemented successfully in several low- and middle-income countries. Although information on outcomes is generally lacking, a large project in Brazil has documented notable impacts on health-system efficiency. Meta-analyses and rigorous trials have documented the benefits of text messaging for improving outcomes such as patients’ self-care. Automated telephone monitoring and self-care support calls have been shown to improve some outcomes of chronic disease management, such as glycaemia and blood pressure control, in low- and middle-income countries. Although large programmes for e-health implementation and research are being conducted in many low- and middle-income countries, more information on the impacts of e-health on outcomes and costs in these settings is still needed.